Differential effects of the new antipsychotic risperidone on sleep and wakefulness in the rat

The effects of risperidone, a new antipsychotic with potent 5-hydroxytryptamine2 (5-HT2) and dopamine-D2 (DA-D2) antagonistic properties, were studied on sleep-wakefulness patterns in rats. Administration of low doses (0.01-0.16 mg/kg i.p.) resulted in a significant increase of deep slow wave sleep (SWS2) and a decrease of wakefulness (W) and light slow wave sleep (SWS1). High doses (0.63-2.5 mg/kg) produced opposite effects. Paradoxical sleep (PS) was significantly reduced over the dose range tested. The increase of SWS2 after low doses of risperidone could be related to a predominant and potent 5-HT2 receptor blocking activity.